1. Field of the Invention
The present invention relates generally to semiconductor packages, and more particularly to a semiconductor package including a uniquely configured leadframe including corner leads which are particularly suited to provide signal routing capability at each of the four corner regions of the semiconductor package.
2. Description of the Related Art
As is well known in the electrical arts, leadframes for use in semiconductor packages are formed by a variety of methods, including mechanically stamping or chemically etching a continuous metal strip. Such metal strip is typically made of copper, iron, a copper alloy, or their equivalents. The leadframe serves multiple functions in the semiconductor package by providing a conductive path to a semiconductor die, an external circuit, and a frame for fixing the semiconductor package to an external device. A growing trend in the electronics industry has been to miniaturize semiconductor packages and hence the leadframes thereof, with currently developed semiconductor packages having a thickness much smaller than those known in the prior art. There has also been a growing trend to increase the number of leads in the leadframe to accommodate the steadily increasing numbers of bond pads or contacts of the semiconductor die of the semiconductor package.
Conventional leadframe designs typically comprise an outer frame having a die paddle disposed within the interior thereof. The die paddle is fixed to the outer frame by a plurality of diagonally extending tie bars which typically extend from respective ones of four corner regions defined by the die paddle. The deficiency of this configuration is that leads which would otherwise be used for signaling cannot be formed in diagonal directions (i.e., at the corners of the die paddle) in the semiconductor package. Though the tie bars may be used for ground or power transmission, they typically cannot be used for signaling purposes, thus providing limitations or constraints in the footprint design of the semiconductor package. The designs of certain semiconductor devices or external devices mandate that leads adapted to transmit input and/or output signals be formed at each of the four corner regions of the semiconductor package. However, as indicated above, in conventional leadframe designs, such signal routing capability is not provided at the four corners of the semiconductor package due to the arrangement of the tie bars thereof. This particular deficiency of conventional leadframe designs is alleviated by the present invention, as will be described in more detail below.